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Originally Posted by 1100 man
As everything changed when you changed C498 (4mfd), I still think this is the cause of the oscillator running way too fast. After all, it was running at the correct frequency before C498 was changed, but there was a sync fault.
Look very carefully at the value on the new capacitor- is it really 4.7mfd? Not 0.47 or 47mfd? Is it actually connected? Check for lifted print or hairline cracks around its legs. Do you still have the original capacitor you could try?
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Sorry all for the late reply, It's definitely 4.7uF but I do still have the original and have replaced it, which seemed to have made no difference. (Picture one is my replacement, Picture 2 is the original)
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The voltage on T4500's collector should be 17.8v, base 7.35v and emitter 6.9v
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Testing this the collector was 17.83, the base was 7.190 and the emitter dropped from around 6.660 to around 6.450 (Written as seen on DMM)
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T4511 C 13.0, B -2.45 and E .014v
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C is around 17.15V, B is 026V (not 2.6) and E is 027V (Again as seen on DMM)
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An important voltage is at TP47 - 7.35v - this is the control voltage to T500's base.
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Tested this and it read around from anywhere between 7.000 to 7.060. It started off around the 7.060 mark and dropped down to 7.000 (Same as what was displayed on the DMM)
I'd do checks tracing backwards from the fault but I'd not be sure at which components to be looking at.
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Might also be worth checking the line discriminator balance control if not already done so as that will affect the voltage at the reactance transistor.
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Where would this be or what would it look like? There's a few controls that I can see but they're for height, linearity and the likes.
Thanks
'77